1. Field of the Invention
This invention relates to the mechanical arts. In particular, it relates to a duct assembly for use in aircraft anti-icing conduit systems.
2. Discussion of the Related Art
As is well-known, jet aircraft engines provide the thrust needed to propel jet aircraft. Additionally, by redirecting a portion of the compressed, bleed air produced by the engines through a conduit system, the air can be used for a variety of other purposes. These other purposes include pressurizing, heating, and cooling the aircraft's cabin, and removing moisture from its front windows. To be effective, the conduit system must not only minimize the escape of the bleed air, but it must withstand the elevated temperatures, often in excess of 650.degree. F., of the bleed air produced by today's jet aircraft.
Another important use for the bleed air is to de-ice the aircraft wings' leading edges, wing slats, and elevons. For example, to de-ice the movable slats located on the leading edge of the aircraft wings, hot, compressed, bleed air is transferred through conduit sections from a supply duct running lengthwise in the wings' leading edge to a spray duct running lengthwise in the wings' slats. The spray duct has openings to deliver the bleed air to the interior surface of the slats.
Special considerations are involved in the anti-icing conduit systems used to de-ice movable portions of the aircraft, such as wing slats and elevons, that must undergo a wide range of motions as they are extended and then retracted. In order to track the movement of these components, the conduit system must contain slidable and rotatable conduit sections. Conventional duct assemblies are formed from metallic, tubular, telescoping conduit sections. To maintain the air pressure within the assembly, each conduit section is sealed with an elastomeric seal. Special, high temperature-resistant elastomeric compositions have been developed for the manufacture of such seals. Nonetheless, the seals still become unstable and their performance over time suffers, when they are exposed to extended or to relatively direct contact by the stream of hot, compressed, bleed air.
Accordingly, there has existed a definite need for an improved duct assembly which not only minimizes the escape of compressed air, but is stable for prolonged periods of time at high temperatures. The present invention satisfies these and other needs and provides further related advantages.